3d imaging, ranging, and/or tracking using active illumination and point spread function engineering

ABSTRACT

Imaging systems and imaging methods are disclosed to estimate a three-dimensional position of an object at a scene and/or generate a three-dimensional image of the scene. The imaging system may include, for example, one or many light sources; an optical system configured to direct light from the one or more light sources into a pattern onto the scene; a mask; a detector array disposed to receive light from the scene through the mask; and at least one processor communicatively coupled with the detector and configured to estimate a depth of a particle within the scene.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.14/934,031filed Nov. 5, 2015, which issued as U.S. Pat. No. 9,967,541 onMay 8, 2018. The Ser. No. 14/934,031 application is a non-provisionalof, and claims the benefit of, U.S. Provisional Patent Application Ser.No. 62/075,746 filed Nov. 5, 2014. The Ser. No. 14/934,031 applicationand the Ser. No. 62/075,746 application are incorporated herein byreference for all purposes.

SUMMARY

An imaging system and an imaging method are disclosed to estimate athree-dimensional position of an object at a scene, track objects orportions of objects in three-dimensional space within a scene, andcreate three-dimensional images. The imaging system may include, forexample, one or many light sources; an optical system configured todirect light from the one or more light sources into a pattern onto thescene; a mask; a detector array disposed to receive light from the scenethrough the mask; and at least one processor communicatively coupledwith the detector and configured to estimate a depth of a particlewithin the scene based on the data collected by the detector array. Insome embodiments, objects or portions of objects can be tracked inthree-dimensional space within the scene based on the data collected bythe detector array. In some embodiments, three-dimensional images may becreated of the scene based on the data collected by the detector array.

In some embodiments, the optical system comprises an active illuminationsystem. In some embodiments, the pattern includes a pattern selectedfrom the list consisting of a spot array pattern, a striped pattern, asinusoidal pattern, and a speckle pattern. In some embodiments thepattern may include a three dimensional pattern or a pattern thatvarious in three dimensions.

In some embodiments, the mask generates a point spread function from thelight from the scene. In some embodiments, the point spread functioncomprises a double helix point spread function. In some embodiments, theimaging system may implement a point spread function that includes oneor more spots of light that describe curves in three-dimensional space.

In some embodiments, the mask includes an optical element such as, forexample, a diffractive optical element, a grating, a Dammann grating, adiffuser, a phase mask, a hologram, an amplitude mask, a spatial lightmodulator, and/or a prism array.

Some embodiments may include a method for estimating a depth of objects(or particles or portions of the objects). The method may includeilluminating a scene with light having a first pattern; directing lightfrom the scene through a mask that generates a point spread functionfrom the light from the scene that varies based on depth within thescene; producing an image of the scene from light that passes throughthe mask using a light detector; and estimating a depth of one or moreobjects within the scene from the image of the scene.

Some embodiments may include a method for estimating a depth of objects(or particles or portions of the objects). The method may includeilluminating a scene with a first light pattern; producing a first imageof the scene after it passes through the mask using a light detector;illuminating the scene with a second light pattern; producing a secondimage of the scene after it passes through the mask using the lightdetector; and estimating a depth of one or more objects within the scenefrom the first image of the second and the second image of the scene.

In some embodiments, the method may also include directing light fromthe scene through a mask that generates a point spread function from thelight from the scene that varies based on depth within the scene.

In some embodiments, the method may also include directing light fromthe scene through a first mask that generates a first point spreadfunction from the light from the scene that varies based on depth withinthe scene; and directing light from the scene through a second mask thatgenerates a second point spread function from the light from the scenethat varies based on depth within the scene.

In some embodiments, the first point spread function comprises a doublehelix point spread function or a cubic phase point spread function. Insome embodiments, the first point spread function may include one ormore spots of light that describe curves in three-dimensional space. Insome embodiments, the first point spread function may have an extendeddepth of field.

In some embodiments, the first pattern includes a pattern selected fromthe list consisting of a spot array pattern, a striped pattern, asinusoidal pattern, and a speckle pattern; and wherein the secondpattern includes a pattern selected from the list consisting of a spotarray pattern, a striped pattern, a sinusoidal pattern, and a specklepattern.

In some embodiments, the first mask includes an optical element selectedfrom the list consisting of an optical element with an extended depth offield, a cubic phase mask, a double helix point spread function mask,diffractive optical element, a grating, a Dammann grating, a diffuser, aphase mask, a hologram, an amplitude mask, a spatial light modulator,and a prism array; and/or the second mask includes an optical elementselected from the list consisting of a cubic phase mask, a double helixpoint spread function mask, diffractive optical element, a grating, aDammann grating, a diffuser, a phase mask, a hologram, an amplitudemask, a spatial light modulator, and a prism array.

These illustrative embodiments are mentioned not to limit or define thedisclosure, but to provide examples to aid understanding thereof.Additional embodiments are discussed in the Detailed Description, andfurther description is provided there. Advantages offered by one or moreof the various embodiments may be further understood by examining thisspecification or by practicing one or more embodiments presented.

BRIEF DESCRIPTION OF THE FIGURES

These and other features, aspects, and advantages of the presentdisclosure are better understood when the following Detailed Descriptionis read with reference to the accompanying drawings.

These and other features, aspects, and advantages of the presentdisclosure are better understood when the following Detailed Descriptionis read with reference to the accompanying drawings.

FIG. 1 illustrates a defocus response of a conventional (e.g., a clearaperture) optical imaging system according to some embodiments.

FIG. 2 illustrates an example of the depth dependence of the DH-PSF withthe defocus parameter according to some embodiments.

FIG. 3 illustrates an example of axial dependence of a point spreadfunction generated by a cubic phase mask according to some embodiments.

FIGS. 4A and 4B illustrate example configurations of a point spreadfunction according to some embodiments.

FIG. 5 illustrates a block diagram of an active dual-channelcomplementary point spread function-engineering digital-optical systemaccording to some embodiments.

FIG. 6 illustrates an imaging and ranging system according to someembodiments.

FIG. 7 shows an illustrative computational system for performingfunctionality to facilitate implementation of embodiments described inthis document.

FIG. 8 illustrates an active illumination system according to someembodiments.

FIGS. 9A-9G illustrate a plurality of examples of projection patternsaccording to some embodiments.

FIG. 10 illustrates an active illumination system according to someembodiments.

FIG. 11 illustrates an active illumination system according to someembodiments.

FIG. 12 illustrates an example method for deriving either or both depthand location information from a scene according to some embodiments.

FIG. 13 illustrates an example method for tracking an object within ascene according to some embodiments.

DETAILED DESCRIPTION

Systems and methods are disclosed for estimating the three-dimensionalposition and/or the range of a particle(s), object(s), or portion of anobject in a scene. Some embodiments may include an active illuminationsystem that is used to illuminate the scene. Some embodiments mayilluminate the scene with an illumination pattern. Some embodiments mayemploy one or more masks (or phase masks) that produce a point spreadfunction that includes depth of field information.

Some passive ranging systems retrieve depth of a scene from images ofdefocus. Often the result of defocus can be an enlarged,rotationally-symmetric, transverse pattern that is consistent with theout-of-focus blurring of objects that may carry limited high spatialfrequency information. Depth from defocus approaches may be attractivefor ranging applications because they can provide range over a widefield of view, with parallel transverse data in contrast to apoint-by-point scanning-based technique. The depth information may becontained in a depth-dependent blur encoded into the image. In manycases this blur may be ambiguous, for example, more than one depth mayproduce the same image as shown in FIG. 1, which illustrates a defocusresponse of a conventional (e.g., a clear aperture) optical imagingsystem according to some embodiments.

Depth-from-defocus systems may adjust focus or use several (e.g.,typically two) fixed focal planes. In some cases, depth estimation maybe provided by the radius of the blur as shown in FIG. 1.

Engineered coded pupil functions may be used to modify a point spreadfunction for enhanced (in depth, transverse and/or global) sensitivity.Some of these techniques may operate under passive and polychromaticillumination.

The Double-Helix point spread function (DH-PSF) may provide anattractive solution for 3D localization. General DH-PSF may besuperpositions of Laguerre-Gauss (LG) modes. For example, for any pointspread function type, optical efficiency, estimation precision, depth offield, side lobes, and/or other parameters affected by the pupil-planephase modulation can be optimized or just improved according to a taskspecific metric such as Fisher information or the Cramer-Rao Lower Bound(CRLB).

For example, a specific design of the DH-PSF may be more suitable forrange estimation than clear aperture systems based on the enhancedprecision in localization of point-like objects. The DH-PSF encodes theaxial position of an object in the orientation of two replicas of theobject in the image (as opposed to encoding with blur). If the object isa point source, the images form a double-helix pattern as the object ismoved through focus as shown in FIG. 2, which illustrates an example ofthe depth dependence of the DH-PSF with the defocus parameter.

Point spread functions may, for example, have limited axial variation.In some cases the point spread function generated by a phase mask (e.g.,a cubic phase mask) may produce a point spread function with anessentially constant profile over an extended depth, as shown in FIG. 3,which shows an example of axial dependence of a point spread functiongenerated by a cubic phase mask, which is one example of depth invariantpoint spread function. There may be many (possibly infinite)possibilities when it comes to generate depth invariant point spreadfunctions. Examples may include point spread functions with Besselbeams, axicons, so called accelerating beams, numerically optimizedpoint spread functions, combinations of Bessel beams, Mathiew beams,Laguerre Gaussian beams, Gaussian-Bessel beams, and/or many others. Insome embodiments, the point spread function may include an opticalelement with an extended depth of field.

In some embodiments, the phase mask may include an amplitude mask, ahologram, or a diffractive optical element. In some embodiments, thephase mask may include a double-helix phase mask, a polarizationinsensitive phase mask, a polarization dependent response for eachspatial location (pixel), an elliptically apertured phase mask, etc. Insome embodiments, the phase mask function can be implemented with areflective device, such as a structured mirror, with a surface profileor varying reflectivity. The phase mask can also be implemented withtransmissive or reflective spatial light modulators, continuous orsegmented, including possibly liquid crystal devices.

In some embodiments, depth estimation may be determined using two ormore engineered phase masks, broadband incoherent light, and/orreconstruction of depth maps for continuous scenes with varying depth.

FIGS. 4A and 4B illustrate example configurations of a point spreadfunction according to some embodiments.

FIG. 10 illustrates an example configuration of active illumination,point spread function coded, 3D imaging and/or ranging system accordingto some embodiments of the invention. In a DH-PSF or other helical pointspread functions a rotation angle may be associated with the estimatedpoint spread function by calculating the angle subtended by thecentroids of each lobe and a frame-of-reference on the detector as shownin FIG. 10. The DH-PSF rotation angle varies accordingly as a functionof axial position as shown in FIG. 10 and can be found experimentally toaccount for the presence of possible aberrations. For example, theDH-PSF may manifest as a pair of intensity lobes that rotate as theobject moves axially or the angle of rotation or the intensity lobes maybe based on the axial position of the object. Alternatively oradditionally, the point spread function may manifest as a pair ofintensity lobes that separate as the object moves axially. In someembodiment, the size of the point spread function as a function of depthencodes depth information. In some embodiments, the changing shape ofthe point spread function with depth provides the depth information.

In some embodiments, the term “scene” may include a collection ofobjects at which the 3D imaging system is aimed with the intention ofimaging and/or measuring. In a biological application, for example, thescene may be a sample, which could be prepared with differentfluorophores, to express different structural or functional aspects ofthe sample. In materials inspection and metrology, as another example,the scene could be a semiconductor, metal, dielectric, etc., at whichthe system is aimed. In photography, as yet another example, the scenemay be a collection of objects that can include humans of which thesystem (or camera) is intended to locate, recognize, and/or analyzetheir gestures and/or actions of the human and/or portions of the humanby means of 3D imagery or ranging measurements. The scene may includethe motion and/or position of the extremities of a human. In 3D printingapplications, as yet another example, the scene can be an object that isscanned for reproduction with additive manufacturing.

In some embodiments, the phrase “active illumination system” may referto an illumination system that delivers light to the scene in a way thatfacilitates 3D information retrieval. The illumination of the scene mayinclude the use of optics that encodes information.

In some embodiments, the light illumination system may include a highlycoherent source that impinges onto a diffractive optical element and/orprojects an array of spots onto the scene as shown in FIG. 5. In someembodiments, the array of spots may have a periodic, random, dynamic,scanning spots, a sparse set of spots, and/or pseudo-random pattern in atransverse plane and/or in 3D within a volume. Furthermore, for example,by modulating or changing the diffractive optical element and/or thesource, the array of spots can be modulated in intensity over time orshifted in location. In some embodiments, the array of spots mayeffectively produce a parallel scanning system consisting of a multitudeof spots in space. The diffractive optical element can be substituted bya refractive optical element, a reflective element, lenslet array, ahologram, a spatial light modulator, an amplitude mask, an imagingsystem, and/or a Dammann grating, etc.

In some embodiments, the illumination system may create a specklepattern on the scene. The speckle pattern, for example, may have variousstatistical characteristics and be either static or dynamic.

In some embodiments, an active illumination system may generate patternscomposed of lines, curves, spots, surfaces, 3D patterns, and/orarbitrary 3D patterns. For example, the active illumination system maygenerate an array of spots that extend in depth as an array ofBessel-like beams. As another example, the active illumination systemmay generate patters composed of so-called non-diffracting beamsgenerated by axicons containing conical surfaces or other surfaces ofrevolution. As another example, the illumination system may include acubic phase mask that produces curved lines in 3D space. As anotherexample, the illumination system may include a cubic phase mask thatincludes so-called accelerating beams. As another example, theillumination system may include a grating such as, for example, aDammann grating, etc., that generates an array of lines and/or modulatedlines. In some embodiments, the illumination system may generate planewaves such as, for example, with oblique incidence and/or superpositionof plane waves.

As another example, the active illumination system may produce a lightpattern that is modulated and/or changed in time. As another example,the active illumination system may produce a light pattern that mayinclude patterns of different colors and/or spectral characteristics. Insome embodiments, the time of arrival of light modulated in time can beused as an additional source of depth information.

In some embodiments the active illumination system may produce a lightpattern that includes a single (or several) spots that may be scannedacross the scene in two or three dimensions. In some embodiments, imagesof the scene may be processed to retrieve 3D information based on lightreflected (or emitted) from one or more particles or objects within thescene. In some embodiments, the information in these images can be usedto construct a cross section of the scene and/or to refocus thesecross-sections.

In some embodiments, the active illumination system may encodeinformation in a coherence function or the polarization of theillumination patterns or structures.

In some embodiments, the active illumination system may include lensesto focus, magnify or demagnify the light patterns and/or lightstructures.

Embodiments of the invention include an imaging and ranging system 600shown in FIG. 6. The system 600 includes one or more light sources 605and an optical system 610 that projects light patterns onto a scene 615.The combination of the light sources 605 and/or the optical system 610may comprise an active illumination system.

The optical system 610 may include one or more phase masks, lenses,diffractive optical elements, gratings, Dammann gratings, diffusers,phase masks, holograms, amplitude masks, spatial light modulators, prismarrays, etc. In some embodiments, the optical system 610 may create oneor more illumination patterns as shown in FIGS. 9A-9G.

The system 600 may also include a detector 620 that collects light fromthe scene 615 through a phase mask 625 and/or other optical elements.The system 600 may also include at least one controller 630 that may beused to determine depth information of various portions of the scenebased on inputs from the detector 620, control the operation of thelight sources 605 and/or control the operation of the detector 620.

In some embodiments, the light source 605 may include a plurality oflight sources. In some embodiments, the light source 605 may alsoinclude a light emitting diode (LED), a super-luminescent LED, a laser,a white light source, a natural light, a pulsed laser, etc. In someembodiments, the light source 605 may project infrared light and/orvisible light.

In some embodiments, the optical system 610 may project light from thelight source 605 into light patterns onto the scene 615. In someembodiments, the optical system 610 may modulate the light from thelight source 605 and/or direct the light from the light source to thescene 615. The optical system 610 may include any number of opticalelements such as, for example, one or more diffractive optical elements,gratings, Dammann gratings, diffusers, phase masks, holograms, amplitudemasks, spatial light modulators, or prism arrays. In some embodiments,the light from the light source 605 may be modulated by a spatial lightmodulator (SLM).

In some embodiments, the optical system 610 may project light patternsonto the scene 615 that change or evolve with depth.

In some embodiments, the optical system 610 may project light patternsonto the scene 615 that encodes information in two-dimensions or threedimensions with spatial variations, temporal variations, a coherencefunction, polarization, and/or the spectral characteristics of thelight, etc.. In some embodiments, the optical system 610 may create amultiplicity of light beams that illuminate at least a portion of theobjects in the scene.

In some embodiments, the detector 620 may be a CCD camera, a CMOScamera, a photodetector, an avalanche photodetector, etc. In someembodiments, the light reaching the detector 620 may be the result ofscattering, transmission, absorption, fluorescence, two/multi-photonfluorescence, high harmonic generation, refraction, and/or diffractionat or from the objects of the scene 615. In some embodiments, the lightfrom the scene 615 may pass through one or more optical elements priorto being collected at the detector 620.

In some embodiments, the detector 620 may provide an image of at leastone object or portions of the object in the scene 615. In someembodiments, the detector 620 may incorporate redundant features of anobject or objects within the scene 615 at offset positions and/or atlateral shifts. In some embodiments, the processor may determine thedepth of the object or objects based on the offset of the redundantfeatures.

In some embodiments, a phase mask 625 may be positioned in the opticalpath between the scene 615 and the detector 620. In some embodiments,the phase mask 625 may generate a three-dimensional point spreadfunctions. In some embodiments, the phase mask 625 may include anynumber of optical elements such as, for example, one or more diffractiveoptical elements, gratings, Dammann gratings, diffusers, phase masks,holograms, amplitude masks, spatial light modulators, and/or prismarrays, etc. In some embodiments, the phase mask 625 may be implementedby a reflective element such as, for example, a deformable mirror, areflective spatial light modulator, etc.

In some embodiments, the phase mask 625 may be transmissive orreflective. In some embodiments, the phase mask 625 may modulate theintensity of light by scattering or absorption of light. In someembodiments, the phase mask 625 may produce an image of a small object(or point source) that changes with the 3D position of the small object.In some embodiments, the phase mask 625 may generate, for each point oflight in the scene 615, one or more spots on the detector 620.

In some embodiments, the phase mask 625 may optimize a depth specificmetric, such as maximizing or increasing the Fisher information withrespect to depth estimation, or minimizing the Cramer Rao lower bound,or mutual information.

In some embodiments, the phase mask 625 may be a transmissive phase maskor a reflective phase mask.

In some embodiments, the controller 630 may include a processor,microprocessor, computer system, etc. For example, the controller 630may include the computer system 700 shown in FIG. 7. In someembodiments, the controller 630 may determine the depth of at least oneor more objects of the scene 615 based on the image shape of a spot oflight from one or more objects in the scene 615. In some embodiments,the controller 630 may determine the depth of at least one or moreobjects of the scene 615 based on the locations of the one or many spotson the image generated by a spot of light from the one or more objectsin the scene 615.

In some embodiments, the overall point spread function of the system maya combination of the point spread functions of the illuminationsubsystem, the optical subsystem between the scene and the detector, andthe reconstruction algorithm. One example of a way for determining thelocation of an object is by the variations of the shape of the pointspread function with location in depth of the object (e.g., the imagegenerated by the object will be a function of the location in depth).Another example of a way for an determining the location (orthree-dimensional position)of an object is by directly illuminating acertain region and then imaging a whole volume. In this example, onlythe object or portion of the object in the region defined by theillumination may generate an image and hence the location (orthree-dimensional position) of the object or portion of the object willbe determined by the region of illumination. As another example, thescene may be illuminated with a spot pattern that includes an array ofisolated spots. The location (or three-dimensional position) of anobject or portion of the object in the scene illuminated by the spotsmay be determined. A processor or controller (e.g., controller 630,processor 825, or processor 1035) for example, may estimate the location(or three-dimensional position) of the object may be made from theimages acquired by the detector(s).

In some embodiments, at least two images of the scene 615 may beobtained by the controller 630 via the detector 620 at the same orsubstantially the same time. In other embodiments, at least two imagesof the scene 615 may be obtained by the controller 630 via the detectorat different times.

In some embodiments, the scene 615 may include at least a portion of orall of a human. In such embodiments, the optical system 610 mayilluminate the human within the scene 615 and the detector 620 maycapture an image of the human within the scene 615, which may berecorded by the controller 630.

In some embodiments, multiple images of a human within the scene 615 maybe captured by the detector 620 and recorded by the controller 630. Thecontroller 630 may track the motion of the human and/or portions of thehuman based on the multiple images of the human and/or other informationprovided by the system 600 or from other sources. In some embodiments,the controller 630 may provide tracking information and/orthree-dimension information of the human and/or portions of the human tocontrol and/or update a user interface such as, for example, a display,speaker, handheld device, etc.

In some embodiments, multiple images of an object or objects within thescene 615 may be captured by the detector 620 and recorded or saved intoa memory location by the controller 630. The controller 630 may trackthe motion of the object or objects based on the multiple images of thehuman and/or other information provided by the system 600 or from othersources. For example, the location of the object or a portion of theobject may be tracked by following the object as it moves within thescene over time. For example, the location of the object or a portion ofthe object may be determined periodically and saved into memory. In someembodiments, the controller 630 may provide tracking information and/orthree-dimension information of the object or objects to control and/orupdate a user interface such as, for example, a display, speaker,handheld device, etc.

In some embodiments, the system 600 may be a part of a three-dimensionalcamera or a microscope. In some embodiments, the system 600 may be apart of a ranging system.

In some embodiments, the scene 615 may include brain tissue comprisingneurons. In some embodiments, the controller 630 may use 3D informationto track the signals produced by neurons. In some embodiments, theoptical system 610 may project one or more light patterns on at leastone neuron.

In some embodiments, at least a portion of the scene may include asurface of material. The three-dimensional characteristics of thesurface may be measured and/or analyzed by the controller 630 based onat least one image captured by the detector.

In some embodiments, at least a portion of the scene may include aportion of a production line. Three-dimensional images of objects on theproduction line may be captured by the detector 620 and/or analyzed bythe controller 630.

In some embodiments, the system 600 may be used as part of a robot. Thecontroller 630 may provide three-dimensional information and/or trackinginformation to the robot based on images of the scene 615 that arecaptured by the detector 620. For example, the system 600 may captureportions of a space to be navigated. The controller 630 may communicateinformation to the robot or be used by the robot to navigate the spacesuch as, for example, by engaging and/or controlling, motors, actuators,pulleys, etc. in response to the information.

In some embodiments, the system 600 may be used as part of a manned orunmanned vehicle. The controller 630 may provide three-dimensionalinformation and/or tracking information to the vehicle based on imagesof the scene 615 that are captured by the detector 620. For example, thesystem 600 may capture portions of a space to be navigated. Thecontroller 630 may communicate information to the vehicle or be used bythe vehicle to navigate the space such as, for example, by engagingand/or controlling, motors, actuators, pulleys, etc. in response to theinformation.

In some embodiments, the system 600 may be used as part of a mobiledevice, a wearable device, and/or a surveillance system. In someembodiments, the system 600 may be used as or as part of a 3D scanner ora 3D printer. In some embodiments, the system 600 may be used as part ofan optical tweezers system.

In some embodiments, the phase mask 625 may generate a spatial lightmodulator. In some embodiments, the phase mask 625 may be implemented bya reflective element such as, for example, a deformable mirror, areflective spatial light modulator, etc.

In some embodiments, the phase mask 625 may generate a double-helixpoint spread function phase-mask. In some embodiments, the Fouriertransform of the sample image can be multiplied by the double-helixpoint spread function transfer function. In some embodiments, everyobject point in the scene may be convolved with two lobes such that theangular orientation of the two lobes may vary depending on the axiallocation of the object above or below focus. For example, the two lobesmay be aligned horizontally when the emitter (or object) is in focus. Asthe emitter is moved towards the objective, the double-helix pointspread function lobes may rotate in the counterclockwise direction. Onthe other hand, if the emitter is moved away from the objective, thelobes may rotate in the clockwise direction.

Alternatively or additionally, as the emitter is moved towards theobjective, the double-helix point spread function lobes may rotate inthe clockwise direction. On the other hand, if the emitter is moved awayfrom the objective, the lobes may rotate in the counterclockwisedirection.

Alternatively or additionally, the phase mask 625 may generate a lateralpoint spread function that cause the lobes in an image to be displacedhorizontally depending on the axial location of the emitter. Forexample, the two lobes may be aligned vertically when the emitter (orobject) is in focus. As the emitter is moved towards the objective, afirst lobe may move to the left and a second lobe may move to the right.On the other hand, if the emitter is moved away from the objective, thefirst lobe may move to the right and the second lobe may move to theleft.

In some embodiments, the phase mask 625 may generate a point spreadfunction that produces a transverse profile composed of multiplepatterns. Each of these patterns may retain its fundamental shape withdefocus yet each pattern may move in different trajectories duringdefocus. In some embodiments, phase mask 625 may include a point spreadfunction that may include one or more spots of light that describecurves in three-dimensional space. In some embodiments, phase mask 625may include a point spread function that may have an extended depth offield.

In some embodiments, the phase mask 625 may generate a point spreadfunction that produces two image lobes that are separated from eachother along a straight line. The two lobes may be separated from eachother (e.g., the line may extend or contract) based on the defocus ofthe emitters. For example, the two lobes may be separated from eachother in the opposite direction.

In some embodiments, the phase mask 625 may generate a point spreadfunction that may produce two lobes that move along two differentstraight lines as the emitter moves relative to the objective lens froma positive defocus position to a negative defocus position and viceversa. In some embodiments, the two straight lines may be parallel toeach other.

In some embodiments, the phase mask 625 may generate a point spreadfunction that may have at least one helix with infinite offset radiusthat degenerates into a straight line. In some embodiments, the pointspread function may have two straight lines with an axis of symmetrycoinciding with the optical axis of the system. In some embodiments, thepoint spread function may have at least a helix with null (zero) pitchsuch that the helix degenerates into a circle or an ellipse. In someembodiments, the point spread function may generate a conical surface inthree-dimensional space. In some embodiments, the point spread functionmay have at least one helix degenerating into a conical section curve.

In some embodiments, a maximum of a point spread function may describe acurve in three-dimensional space that turns around an axis at a constantor continuously varying distance (offset) while moving in the directionparallel to the axis. In some embodiments, a maximum of the point spreadfunction describes a curve in three-dimensional space similar to a helixwith varying offset from a helix axis and/or a pitch, and when both theaxis and offset are constant, the point spread function describes ahelical curve.

The computational system 700 (or processing unit) illustrated in FIG. 7can be used to perform any of the embodiments of the invention. Forexample, the computational system 700 can be used alone or inconjunction with other components. As another example, the computationalsystem 700 can be used to perform any calculation, solve any equation,perform any identification, and/or make any determination describedhere. The computational system 700 includes hardware elements that canbe electrically coupled via a bus 705 (or may otherwise be incommunication, as appropriate). The hardware elements can include one ormore processors 710, including, without limitation, one or moregeneral-purpose processors and/or one or more special-purpose processors(such as digital signal processing chips, graphics acceleration chips,and/or the like); one or more input devices 715, which can include,without limitation, a mouse, a keyboard, and/or the like; and one ormore output devices 720, which can include, without limitation, adisplay device, a printer, and/or the like.

The computational system 700 may further include (and/or be incommunication with) one or more storage devices 725, which can include,without limitation, local and/or network-accessible storage and/or caninclude, without limitation, a disk drive, a drive array, an opticalstorage device, a solid-state storage device, such as random accessmemory (“RAM”) and/or read-only memory (“ROM”), which can beprogrammable, flash-updateable, and/or the like. The computationalsystem 700 might also include a communications subsystem 730, which caninclude, without limitation, a modem, a network card (wireless orwired), an infrared communication device, a wireless communicationdevice, and/or chipset (such as a Bluetooth(r) device, a 802.6 device, aWi-Fi device, a WiMAX device, cellular communication facilities, etc.),and/or the like. The communications subsystem 730 may permit data to beexchanged with a network (such as the network described below, to nameone example) and/or any other devices described in this document. Inmany embodiments, the computational system 700 will further include aworking memory 735, which can include a RAM or ROM device, as describedabove.

The computational system 700 also can include software elements, shownas being currently located within the working memory 735, including anoperating system 740 and/or other code, such as one or more applicationprograms 745, which may include computer programs of the invention,and/or may be designed to implement methods of the invention and/orconfigure systems of the invention, as described in this document. Forexample, one or more procedures described with respect to the method(s)discussed above might be implemented as code and/or instructionsexecutable by a computer (and/or a processor within a computer). A setof these instructions and/or codes might be stored on acomputer-readable storage medium, such as the storage device(s) 725described above.

In some cases, the storage medium might be incorporated within thecomputational system 700 or in communication with the computationalsystem 700. In other embodiments, the storage medium might be separatefrom the computational system 700 (e.g., a removable medium, such as acompact disc, etc.), and/or provided in an installation package, suchthat the storage medium can be used to program a general-purposecomputer with the instructions/code stored thereon. These instructionsmight take the form of executable code, which is executable by thecomputational system 700 and/or might take the form of source and/orinstallable code, which, upon compilation and/or installation on thecomputational system 700 (e.g., using any of a variety of generallyavailable compilers, installation programs, compression/decompressionutilities, etc.), then takes the form of executable code.

Some embodiments may include the simultaneous engineering of anillumination pattern and/or a point spread function of an imaging systemto recover depth information of a scene and/or objectbrightness/reflectivity/fluorescence to characterize the scene. Thesystem performance limits may be used to design the illumination and/orimaging parts of the system jointly or separately. The Performancelimits such as the Cramer-Rao Bound may also help compare with othermethods such as the standard clear circular aperture used in depth fromdefocus methods.

In some embodiments, it may be possible to use diverse and/orcomplementary illuminations and/or engineered point spread functions toextract information from the scene that is normally lost with classicalimaging systems. For instance, the DH-PSF may provide high depthdiscrimination over an extended depth range, while an axicon or a cubicphase mask may provide in-focus information for similar depth of field.A spot array (random or lattice) may be used to facilitate the decodingof the depth information on a point by point basis and/or on a widefield of view. The spot array may be modified over time to recover depthfrom different regions of interest or from the whole scene. Thesecapabilities may be complementary and/or amenable for joint design andjoint digital post-processing. The basic property of interest in theDH-PSF and other point spread functions used on the passive side of thesystem is its rapid change through defocus that improves the sensitivityto depth and facilitates its estimation. The use of efficient phasemasks for both the spot array generation and the passive point spreadfunction engineering enables high light throughput, which is criticalfor low power consumption situations.

The systems and methods presented here may be amenable to multi-apertureparallel implementation in arrangements similar to light field cameras.

In some embodiments, as opposed to stereo imaging, the illuminationand/or point spread function engineering solution may not experiencecorrespondence and occlusion problems. Therefore, the systems areattractive for many 3D applications such as 3D scanners, surfaceprofilometry, neuronal imaging, fluorescence microscopy, interactivegames, surveillance, robotics, and mobile applications.

The systems may be amenable to time sequential imaging performed withcomplementary illuminations and point spread functions implemented inparallel with a dual aperture system or via a beam splitter device witheither one or more cameras.

FIG. 8 illustrates an illumination system 800 according to someembodiments. The light source 805 may illuminate a scene 810 with one ormore projection light patterns (see, for example, the light patternsshown in FIGS. 9A-9G). The scene 810 may include one or more objectsand/or samples.

An optical system 815 may direct the light from the scene 810 throughone or more optical elements 816, 818 and/or a mask 817 to a detectorarray 820. The detector array 820 may be coupled with a processor 825(e.g., computer, controller, etc.) to produce 3D images and/or rangemaps. The mask 817 may include any phase mask described in thisdocument.

The light source 805 may illuminate the scene 810 with any number ofprojection patterns. These projection patterns may be produced, forexample, using any number of optical elements, masks, and/or filters.

FIGS. 9A-9G illustrate a plurality of examples of projection patterns.In some embodiments, a projection pattern may include a spot array, forexample, as shown in FIG. 9A. The spot array may, for example, beperiodic, aperiodic, quasi-periodic, etc.

In some embodiments, the projection pattern may have a striped orsinusoidal pattern as shown in FIGS. 9B, 9C, 9D, and/or 9E. Theseprojection patterns, for example, may be in different directions, havedifferent colors and/or different spatial frequencies;

In some embodiments, the projection pattern may have a low contrastprojection pattern and/or low coherence projection pattern as shown inFIG. 9F.

In some embodiments, the projection pattern may have a random specklepattern as shown in FIG. 9G.

In some embodiments, the pattern may include a three dimensional patternor a pattern that various in three dimensions.

In some embodiments, the illumination pattern may be created by passinglight from a light source through one or more optical elements thatinclude mirrors, masks, gratings spatial light modulators, etc.

In some embodiments, the projection pattern may include a single spot ofvarious sizes and or shapes (e.g., circular, oval, polygonal, etc.). Insome embodiments, the projection pattern may also include any type of 3Dprojection pattern such as, for example, arrays of lines and/orBessel-like beams, 3D speckle patterns, and/or curved lines as thosegenerated by so-called accelerating beams. Any number of combinations ofprojection patterns may also be used. Various other projection patternsmay be used.

In some embodiments, the spot pattern may include a sparse set of spots,dynamically changing spots, scanning spots, an array of spots that moveindependently, etc.

FIG. 10 illustrates another illumination system 1000 according to someembodiments. The active illumination system 1000 a light source 1005 mayilluminate a scene 1015. In some embodiments, the light source 1005 mayproduce light with a spot array pattern. In some embodiments, the spotpattern may be created through a mask 1010 or any other filter. In someembodiments, the mask 1010 may include components described inconjunction with optical system 610. In some embodiments, the spotpattern may include any pattern described in conjunction with FIGS.9A-9G. The scene 1015 may include one or more objects and/or samples.

Light 1020 from the scene 1015 may be imaged through an optical systemthat may include one or more lenses, one or more optical elements, oneor more masks 1025, and/or a detector array 1030. The light 1020 mayinclude all the spots or a subset of the spots illuminated on the scene1015. The processor 1035 may be coupled with the detector array 1030and/or may be configured (e.g., programmed with computer readablemedium) to produce a point spread function 1040 for each or a subset ofthe spots. The shape, orientation, and/or position of the point spreadfunction 1040 may encode the depth of the portion of the scene beingilluminated such as, for example, each or a subset of the spots.

In some embodiments, the point spread function 1040 may include one ormore spots of light that describe curves in three-dimensional space. Insome embodiments, the point spread function 1040 may include a pointspread function that may have an extended depth of field.

In some embodiments, the processor 1035 may use algorithms such as, forexample, centroiding functions, likelihood functions, Bayesianfunctions, matching pursuit functions, correlations, and/or convexoptimization methods. In some embodiments, the processor may output 3Dinformation and/or depth information of the scene; and/or combine the 3Dinformation and/or depth information of the scene with other data. Insome embodiments, the processor may also output 3D images and/or rangemaps.

The mask 1010 and/or the mask 1025 may include any phase mask describedin this document.

The illumination system, light source, mask 1010, optical system, mask1025, detector array 1030, and/or processor 1035 may be part of a 3Dimaging and ranging system and/or be coupled within a housing.

In some embodiments, a total system point spread function may bedetermined and/or used for image creation, objection localization,ranging estimation, etc. The total system point spread function may bethe sum (or product) of the point spread functions of the illuminationsubsystem, the imaging subsystem, and/or the post processing system. Ifthe system includes other elements, then the point spread function fromthese elements may be included in the total point spread function. Insome embodiments, the total point spread function may be experimentallydetermined or determined during calibration by, for example, byilluminating a known scene at different three dimensional locationsunder various illumination conditions and determining the point spreadfrom the detected light.

In some embodiments, light detected at the detector array may passthrough a mask on the illumination side, the detection side, or both. Insome embodiments, the light may alternately pass through one or both amask on the illumination side, the detection side.

FIG. 11 illustrates an active illumination method 1100 according to someembodiments. One or more steps of the method 1100 may be implemented, insome embodiments, by one or more components of the system 600 of FIG. 6,illumination system 800 of FIG. 8, or illumination system 1000 of FIG.10. Although illustrated as discrete blocks, various blocks may bedivided into additional blocks, combined into fewer blocks, oreliminated, depending on the desired implementation.

At block 1105 a scene may be illuminated with a first light pattern in afirst time period. The scene, for example, may include the scene 615,the scene 810, and/or the scene 1015. The first light pattern mayinclude, for example, a light pattern shown in FIGS. 9A-9G or any otherlight pattern described in this document. In some embodiments, the firstlight pattern may be generated with an active illumination device.

At block 1110, in the first time period, light from the scene may bedirected through a first optical system having a first point spreadfunction. The first optical system, for example, may include the opticalsystem 815. The first optical system, for example, may include one ormore masks such as, for example, mask 1025 or mask 817 or any other maskdescribed in this document. The first point spread function, forexample, may include any point spread function described in thisdocument.

At block 1115 the light from the scene after being illuminated with thefirst light pattern and/or after being passed through the first opticalsystem may be detected at a light detector and a first image may becreated.

For example, if the first mask generates a double helix point spreadfunction, then the first image may include an image or portions of animage that rotates with a rotation angle that varies as a function ofaxial position. Alternatively or additionally, the point spread functionmay manifest as a pair of intense lobes in the first image that separateor rotate as the object moves axially. In some embodiment, the size ofthe point spread function may encode depth information. In someembodiments, the changing shape of the point spread function may encodedepth information. For example, a cylindrical lens acting as the phasemask may encode an astigmatic point spread function.

At block 1120 the scene may be illuminated with a second light patternat a second time period. The second light pattern may include, forexample, a light pattern shown in FIGS. 9A-9G or any other light patterndescribed in this document. The first light pattern and the second lightpattern may be from the same or different light sources and/or maycomprise the same or different light patterns. In some embodiments, thesecond light pattern may be generated with an active illuminationdevice.

At block 1125, during the second time period, light from the scene maybe directed through a second optical system having a second point spreadfunction. The second optical system, for example, may include theoptical system 815. The second optical system, for example, may includeone or more masks such as, for example, mask 1025 or mask 817 or anyother mask described in this document. The second point spread function,for example, may include any point spread function described in thisdocument.

In some embodiments, the first optical system and the second opticalsystem may include the same optical system. In some embodiments, thefirst optical system and the second optical system may include differentoptical systems. In some embodiments, the first point spread functionand the second point spread function may include the same point spreadfunction. In some embodiments, the first point spread function and thesecond point spread function may include different point spreadfunctions.

At block 1120 the light from the scene after being illuminated with thesecond light pattern and/or after being passed through the secondoptical system may be detected at a light detector and a second imagemay be created.

For example, if the second mask generates a double helix point spreadfunction, then the second image may include an image or portions of animage that rotates with a rotation angle that varies as a function ofaxial position. Alternatively or additionally, the point spread functionmay manifest as a pair of intense lobes in the second image thatseparate or rotate as the object moves axially. In some embodiment, thesize of the point spread function may encode depth information. In someembodiments, the changing shape of the point spread function may encodedepth information. For example, a cylindrical lens acting as the phasemask may encode an astigmatic point spread function.

At block 1135 the 3D location and/or position of portions of the scenemay be estimated based on light detected at the detector in the firsttime period and light detected at the detector in the second timeperiod. In some embodiments, the method 1100 may include illuminatingthe scene with additional illumination patterns and/or additionaloptical systems with additional point spread functions (or masks) may beused during additional time periods.

In some embodiments, the detected light may produce a plurality of spotswith one or more intensity lobes. In some embodiments, the angularrotation of one or more lobes may be used at least in part to determinethe three-dimensional range or location of portions of the scene.

One or more optical systems that include one or more phase masks (e.g.,any phase mask described in this document) may direct light from thescene to one or more detector arrays to create a one or more imageframes of the scene such as, for example, with a point spread function.A processor may then use the data from the one or more image frames toestimate 3D location of data and/or 3D shapes of the scene.

FIG. 12 illustrates an example method 1200 for deriving either or bothdepth and location information from a scene according to someembodiments. At block 1205, the method begins by illuminating a scenewith a light source. Any type of light source may be used.

At block 1210, an illumination pattern may be generated. Theillumination pattern, for example, may be generated using an opticalsystem with an active illumination device such as, for example, aphase/amplitude mask, a diffuser, diffractive optics, etc. In someembodiments, the illumination pattern may include a plurality of spots.

At block 1215, light from the scene may be scattered, emitted,reflected, refracted, or some combination thereof from all or a portionof the scene. The light from the scene may also be light that isfluorescing light from portions of the scene. The light from the scenemay also be nonlinearly generated harmonic light. The light from thescene may modulated by a phase or amplitude mask.

At block 1220, the light from scene may be detected at the detectorarray. In some embodiments, the intensity pattern resulting fromphase/amplitude mask modulation may be detected.

At block 1225, the range, the location, or some combination thereof maybe determined based on the shape, pattern, intensity, angular rotation,or some combination thereof of the light detected at the detector array.In some embodiments, the light may produce a plurality of spots with oneor more intensity lobes. In some embodiments, the angular rotation ofone or more lobes may be used at least in part to determine thethree-dimensional range or location of portions of the scene.

At block 1230, the depth, location, or some combination thereof may beoutput. The output may include an output to another device, to anotherprocessing module, another software module, to storage, or somecombination thereof.

FIG. 13 illustrates an example method 1300 for tracking an object withina scene according to some embodiments. At block 1305 the location of anobject can be found within a scene using, for example, processor 1035and/or processor 825 and/or method 1100 or method 1200. At block 1310,the object may be tracked within the scene. For example, the object maybe tracked by determining or estimating the object or portions of theobject within the scene over time.

Blocks 1315 and/or 1320 may be implemented using the various embodimentsdescribed in this document. At block 1315, feedback that is based on thetracking of the object may be provided to another application, module,process, or some combination thereof. At block 1320, the feedback may beprocessed at the other application.

The term “substantially” means within 5% or 10% of the value referred toor within manufacturing tolerances.

Various embodiments are disclosed. The various embodiments may bepartially or completely combined to produce other embodiments.

Numerous specific details are set forth in this document to provide athorough understanding of the claimed subject matter. However, thoseskilled in the art will understand that the claimed subject matter maybe practiced without these specific details. In other instances,methods, apparatuses, or systems that would be known by one of ordinaryskill have not been described in detail so as not to obscure claimedsubject matter.

Some portions are presented in terms of algorithms or symbolicrepresentations of operations on data bits or binary digital signalsstored within a computing system memory, such as a computer memory.These algorithmic descriptions or representations are examples oftechniques used by those of ordinary skill in the data processing art toconvey the substance of their work to others skilled in the art. Analgorithm is a self-consistent sequence of operations or similarprocessing leading to a desired result. In this context, operations orprocessing involves physical manipulation of physical quantities.Typically, although not necessarily, such quantities may take the formof electrical or magnetic signals capable of being stored, transferred,combined, compared, or otherwise manipulated. It has proven convenientat times, principally for reasons of common usage, to refer to suchsignals as bits, data, values, elements, symbols, characters, terms,numbers, numerals, or the like. It should be understood, however, thatall of these and similar terms are to be associated with appropriatephysical quantities and are merely convenient labels. Unlessspecifically stated otherwise, it is appreciated that throughout thisspecification discussions utilizing terms such as “processing,”“computing,” “calculating,” “determining,” and “identifying” or the likerefer to actions or processes of a computing device, such as one or morecomputers or a similar electronic computing device or devices, thatmanipulate or transform data represented as physical, electronic, ormagnetic quantities within memories, registers, or other informationstorage devices, transmission devices, or display devices of thecomputing platform.

The system or systems discussed in this document are not limited to anyparticular hardware architecture or configuration. A computing devicecan include any suitable arrangement of components that provides aresult conditioned on one or more inputs. Suitable computing devicesinclude multipurpose microprocessor-based computer systems accessingstored software that programs or configures the computing system from ageneral-purpose computing apparatus to a specialized computing apparatusimplementing one or more embodiments of the present subject matter. Anysuitable programming, scripting, or other type of language orcombinations of languages may be used to implement the teachingscontained in this document in software to be used in programming orconfiguring a computing device.

Embodiments of the methods disclosed in this document may be performedin the operation of such computing devices. The order of the blockspresented in the examples above can be varied—for example, blocks can bere-ordered, combined, and/or broken into sub-blocks. Certain blocks orprocesses can be performed in parallel.

The use of “adapted to” or “configured to” in this document is meant asopen and inclusive language that does not foreclose devices adapted toor configured to perform additional tasks or steps. Additionally, theuse of “based on” is meant to be open and inclusive, in that a process,step, calculation, or other action “based on” one or more recitedconditions or values may, in practice, be based on additional conditionsor values beyond those recited. Headings, lists, and numbering includedin this document are for ease of explanation only and are not meant tobe limiting.

While the present subject matter has been described in detail withrespect to specific embodiments thereof, it will be appreciated thatthose skilled in the art, upon attaining an understanding of theforegoing, may readily produce alterations to, variations of, andequivalents to such embodiments. Accordingly, it should be understoodthat the present disclosure has been presented for-purposes of examplerather than limitation, and does not preclude inclusion of suchmodifications, variations, and/or additions to the present subjectmatter as would be readily apparent to one of ordinary skill in the art.

That which is claimed:
 1. A method comprising: illuminating a scene withfirst light having a pattern, the pattern changing with depth; directingsecond light from the scene through an optical system that includes amask, wherein the optical system generates a point spread function thatvaries based on depth within the scene, wherein the second lightcomprises light provided by the scene responsive to illumination by thefirst light; producing an image of the scene from the second light thatpasses through the mask using a light detector; and estimating a depthof one or more objects within the scene from the image of the scene. 2.The method according to claim 1, wherein the pattern includes a patternselected from the list consisting of a spot array pattern, a stripedpattern, a sinusoidal pattern, a pattern of a sparse set of spots,dynamically changing spot pattern, a scanning spot pattern, a pattern ofspots that move independently, and a speckle pattern.
 3. The methodaccording to claim 1, wherein the depth of the one or more objects isestimated based on the representation of the point spread function inthe image of the scene.
 4. The method according to claim 1, wherein thepoint spread function comprises a double helix point spread function. 5.The method according to claim 1, wherein the mask includes an opticalelement selected from the list consisting of an optical element with anextended depth of field, a cubic phase mask, a double helix point spreadfunction mask, diffractive optical element, a grating, a Dammanngrating, a diffuser, a phase mask, a hologram, an amplitude mask, aspatial light modulator, and a prism array.
 6. The method according toclaim 1, wherein the second light is the result of one or more of thefollowing: scattering, transmission, absorption, fluorescence, two ormulti-photon fluorescence, high harmonic generation, refraction, and/ordiffraction at or from the objects of the scene.
 7. A method comprising:illuminating a scene with a first light that has a first light pattern;generating a first image of the scene from second light from the scenethat passes through a first mask using a light detector, wherein thesecond light comprises light provided by the scene responsive toillumination by the first light; illuminating the scene with a thirdlight that has a second light pattern that is different from the firstlight pattern; generating a second image of the scene from fourth lightfrom the scene that passes through a second mask using the lightdetector, wherein the fourth light comprises light provided by the sceneresponsive to illumination by the third light; and estimating a depth ofone or more objects within the scene from the first image of the sceneand/or the second image of the scene.
 8. The method according to claim7, wherein the first mask and the second mask are the same mask.
 9. Themethod according to claim 7, further comprising generating athree-dimensional image of the scene from the first image of the sceneand the second image of the scene.
 10. The method according to claim 7,wherein: the first mask generates a first point spread function from thesecond light from the scene that varies based on depth within the scene;and the second mask generates a second point spread function from thefourth light from the scene that varies based on depth within the scene.11. The method according to claim 10, wherein either or both the firstpoint spread function and the second point spread function comprises apoint spread function selected from the list consisting of a doublehelix point spread function, a helical point spread function, anextended depth of field point spread function, and a cubic phase pointspread function.
 12. The method according to claim 7, wherein the firstlight pattern includes a pattern selected from the list consisting of aspot array pattern, a striped pattern, a sinusoidal pattern, and aspeckle pattern; and wherein the second light pattern includes a patternselected from the list consisting of a spot array pattern, a stripedpattern, a sinusoidal pattern, and a speckle pattern.
 13. The methodaccording to claim 7, wherein either or both the first mask and thesecond mask include an optical element selected from the list consistingof an optical element with an extended depth of field, a cubic phasemask, a double helix point spread function mask, diffractive opticalelement, a grating, a Dammann grating, a diffuser, a phase mask, ahologram, an amplitude mask, a spatial light modulator, and a prismarray.
 14. A method comprising: illuminating a scene with first lighthaving a pattern, the pattern encoding information in a coherencefunction, or in the polarization state of the pattern; directing secondlight from the scene through an optical system that includes a mask thatgenerates a point spread function that varies based on depth within thescene, wherein the second light comprises light provided by the sceneresponsive to illumination by the first light; producing an image of thescene from the second light that passes through the mask using a lightdetector; and estimating a depth of one or more objects within the scenefrom the image of the scene.
 15. The method according to claim 14,wherein the pattern includes a pattern selected from the list consistingof a spot array pattern, a striped pattern, a sinusoidal pattern, apattern of a sparse set of spots, dynamically changing spot pattern, ascanning spot pattern, a pattern of spots that move independently, and aspeckle pattern.
 16. The method according to claim 14, wherein the depthof the one or more objects is estimated based on the representation ofthe point spread function in the image of the scene.
 17. The methodaccording to claim 14, wherein the point spread function comprises adouble helix point spread function.
 18. The method according to claim14, wherein the mask includes an optical element selected from the listconsisting of an optical element with an extended depth of field, acubic phase mask, a double helix point spread function mask, diffractiveoptical element, a grating, a Dammann grating, a diffuser, a phase mask,a hologram, an amplitude mask, a spatial light modulator, and a prismarray.
 19. An imaging system, comprising: a laser; an optical systemincluding a mask, the optical system configured to: illuminate a scenewith first light from the laser, the first light having a pattern, thepattern changing with depth; direct second light from the scene throughthe mask, wherein the optical system generates a point spread functionthat varies based on depth within the scene, wherein the second lightcomprises light provided by the scene responsive to illumination by thefirst light; a light detector configured to produce an image of thescene from the second light that passes through the mask; and at leastone processor communicatively coupled with the light detector andconfigured to estimate a depth of one or more objects within the scenefrom the image of the scene.
 20. The imaging system according to claim19, wherein the pattern includes a pattern selected from the listconsisting of a spot array pattern, a striped pattern, a sinusoidalpattern, a pattern of a sparse set of spots, dynamically changing spotpattern, a scanning spot pattern, a pattern of spots that moveindependently, and a speckle pattern.
 21. The imaging system accordingto claim 19, wherein the depth of the one or more objects is estimatedbased on the representation of the point spread function in the image ofthe scene.
 22. The imaging system according to claim 19, wherein thepoint spread function comprises a double helix point spread function.23. The imaging system according to claim 19, wherein the mask includesan optical element selected from the list consisting of an opticalelement with an extended depth of field, a cubic phase mask, a doublehelix point spread function mask, diffractive optical element, agrating, a Dammann grating, a diffuser, a phase mask, a hologram, anamplitude mask, a spatial light modulator, and a prism array.
 24. Theimaging system according to claim 19, wherein the second light is theresult of one or more of the following: scattering, transmission,absorption, fluorescence, two or multi-photon fluorescence, highharmonic generation, refraction, and/or diffraction at or from theobjects of the scene.